A common occurrence in improv is the following:
Joe starts doing a motion. (maybe he's pretending to flip burgers)
Patty comments on what he's doing. (she makes a comment like, "you're flipping burgers again.")
In improv, that seems like a pretty normal thing to do. Someone's miming something, might as well let everyone know what they're doing. Although, this isn't the right thing to do because it's not what normal people do when they're interacting, and it's bad drama.
Unless your name is Captain Obvious, you don't usually come into a room and point out exactly what's going on. How many times when you enter the kitchen, do you say, "looks like you're cooking?" Not too often. This bad habit of improv, let's call it "Captain Obvious," makes a pretty good gag (remember Rob Schneider's copy man on SNL.... "Joe, Joe-arino... makin' copies. The copy-meister...etc."), but a pretty lame start to a scene.
Instead, a better thing to do is to allow the movements you and your partner make to inform the scene---namely as to the environment, what sort of character your partner might be, etc. Pointing out the "obviousness" (don't know if that's a word, so it's quoted) doesn't move the scene along, except to nail down that in fact, that person is doing something... now what?